Patent GB-157721-A (GB)
Title: Improvements in and relating to braking systems for electrically driven vehicles
IPC: B60T13/66
Filed: 1921-01-10
Abstract: 157,721. British Thomson - Houston Co., Ltd., (Assignees of Hamilton, W. S. H.). March 25, 1918, [Convention date]. Fluid-pressure.-Electric locomotives or other train units provided with an electric brake, for instance, a regenerative brake and an air brake, have means for cutting out the air brake in respect of service applications thereof when the electric brake is operative or operative to a substantial degree and for cutting out the electric brake in all emergency applications of the air brake or in such as are effected by the engineer, The driving motors may be cut out with the electric brake. The air brake system described is of the kind described also in Specification 117,647. The brakes may be applied on the locomotive alone by admitting air from the main reservoir MR through the engineer's valve 10 and pipe 20 directly to the chambers AC, 38 of the distributor DV to move the valve 39 thereby supplying main reservoir air to the brake cylinder BC. The pressure in the train-pipe 12 is reduced by the engineer's valve 11 to effect a service or emergency application of the brakes throughout the train, air being supplied to the chambers AC and 38<1> of the valve DV in this case from the chamber PC bv the valve 41 and the brakes on other vehicles being applied by the usual triple valves TV. Fig. 2 shows a developed view of the valves 10, 11 and connections. Reducing valves 210, 211 are interposed in themain reservoir connections 13<1>, 205. The equalizing valve EP is connected to the train-pipe 12 and to the pipe 18 from the equalizing reservoir ER. The pipes 2C and 21 are connected to the application chambers AC, 38<1> of the valve DV, 19 is the exhaust pipe and 15 is a pipe connected to the switch actuating-cylinder 16 and to a port in the valve 11 which is commonly used for sanding apparatus. The positions of the valve 10 are :-Release, Re; running, R; lap, L ; slow and quick application, Sl and Q; and these of the valve 11 are :-Release, Re<1>; running, R<1>; holding. H<1>: lap. L<1>; service and emergency application. Sand E. In the slow application position Sl of the valve 10 air is supplied to the valve DV through a restricted port in this valve. If the valve 11 is placed in the holding position H<1> after an application, the train-pipe is charged through the reducing valve 210 thereby releasing the brakes on the coaches, but as the chambers AC, 38<1> of the valve DV are not opened to exhaust the locomotive brakes are not released. The motor system includes the motor A1, A2 having series fields F1, F2, generators G1, G2 for exciting the fields F1, F2 during regenerative braking and shunt and series fields S1, S2' f1, f2 for the generators G1, G2. In all positions of the master controller MC other than the "off" position, a battery B or other source is normally connected to segment 92 of the controller through the switch 27 and conductor 26. In the first six positions of the controller MC the motors are connected in series, the circuit being from the trolley T through resistances 79 - - 83 selected by the contactors 76 - - 91 and 87 - - 88, the conductor 88<1>, armature A2, field F<2>, contactor 77, armature A1, field F1, fields S1, S2 to earth. In positions VII - - X of the controller MC the motors are connected in parallel the circuits from the trolley being in this case through certain of the resistances, the contactor 89, armature A1, F1, fields S1, S2 to earth and through the conductor 88<1>, armature A2, field F2, and contactor 90 to earth. The contactor 88 is closed in parallel running to establish an equalizing connection between the motors. To effect regenerative braking the controller MC is placed in the full series or parallel position VI or X, and the braking controller BrC is moved successively to positions I - - VI whereby contactors C5, C6 are first closed to connect the generators G1, G2 to the motor fields F1, F2 and the contactors 94 - - 99 are successively energized to cut out the resistances R in the circuit of the shunt fields f1, f2 of the generators G1, G2- The switch 27 through which the battery B is connected to the controllers is normally held closed by a latch 22 connected to the piston 17 and when the engineer's valve 11 is in the emergency position E, Fig. 2, the cylinder 16 is connected to the main reservoir MR so that the switch is opened thereby cutting out the motors and rendering the regenerative braking impossible. A blow hole in the cylinder 16 permits the return of the latch 22 and the switch 27 is reclosed by energizing a magnet 28 through contacts c1, c4 on the controller MC. If it is desired that emergency applications brought about by a break in the train-pipe as well as by the engineer's valve shall render the regenerative brake inoperative, the device shown in Fig. 3 is used. The chamber 59 is connected by the pipe 57 to the train-pipe and air normally feeds therefrom through the groove 217 to the chamber 58 and to the reservoir 74, the valve 61 connecting the chamber 75 to exhaust. The latch 62, 65 is in these conditions engaged to hold closed the switch 70, in the motor control circuit. If a service reduction in train-pipe pressure is made the piston 60 moves to the right, but is stopped by the spring 220 without disengaging the latch, the pressure in the reservoir 74 and chamber 58 being reduced by connection with the chamber 75 through the valve 61 and passage 218 as shown. An emergency reduction causes the piston 60 to move the stem 64 to the right to disengage the latch and open the switch. The air brakes of the locomotive are cut out in service applications when the regenerative brake is in operation by a valve 34, Fig. 1, which opens the chamber 38<1> of the valve DV to atmosphere when the magnet 29 is energized. This may be effected in the first position of the braking controller BrC or if it is desired to permit a simultaneous moderate action of both the air and electric brake, in the fourth (as shown) or other position, the contact 31 connected to the magnet 29 being then controlled also to the battery B. The air brakes on the other vehicles of the train are unaffected.